Two weeks and a day after his whirlwind arrival on the British athletics scene, Malachi Davis gets to run in the red, white and blue of the Great Britain team this afternoon. It is sure to be another high-profile, high-pressure occasion for the erstwhile unknown quarter-miler.

When he lines up for the 400m in the Norwich Union International at the Alexander Stadium in Birmingham, the opposition will just happen to include his former compatriots from the United States. Davis was a US citizen and athlete until FedEx delivered a British passport to his home in Brentwood - a Los Angeles suburb along Sunset Boulevard from Hollywood, Beverly Hills and Bel Air - two days before his appearance at the British Olympic trials in Manchester.

The occasion is sure to stir up more of the hysteria that has surrounded the somewhat bewildered Californian on his maiden, extended, voyage to the land of his Cockney mother: along the lines of the "Malachi Malarkey" and "Instant Brit" headlines, and the steamed-up Radio Five presenter putting it to him that "it was not really fair to get hold of a British passport at the last minute".

Not that Davis is allowing the critical fuss to get to him. He is taking it all in his unruffled stride. As well he might. At 26, the graduate of the University of California, Los Angeles, has overcome something far more formid-able than a chorus of disapproval. As he relates: "I was diagnosed with cancer at the age of five. It was two weeks before my sixth birthday. That's when my dad told me."

Davis had been diagnosed with Burkitt's Lymphoma. He was moved from his sickbed in the family home in Sacramento to the cancer ward at the nearby Kaiser Hospital.

"I was too young at the time to realise how serious it was," he continues. "I didn't realise that until I got a lot older. It's a disease that takes a lot of lives. Getting over it is definitely something that I don't take for granted. I'm thankful for everything I've achieved and everything I have - just to have my health. I'm very, very grateful to have my health."

Since the final announcement of the British track-and-field team last Tuesday morning, Davis has an Olympic place to go with his good health. For all the outrage that his belated attempt to gain selection has attracted, mostly from sections of the media, his graduation to Olympian status is above all else a story of inspiration.

As he says: "It means an awful lot to me to get to the Olympic Games, and to a lot of people who supported me. It might even be something for cancer patients out there, people going through the disease right now. I will gladly help others who have the disease. I can tell them that there are people who survive it and go on to lead prosperous lives. I'm proving it.

"I was bedridden for a long time and I can remember being extremely sick. But by the age of nine I was cured. It was completely out of the system. As I've grown up, I've come into contact with people who have cancer and it's been a motivating story for them. That's given me strength and it's given them strength.

"I'm just happy to be here. I'm thrilled to be running, thrilled to have my health. And thrilled that I'm going to the Olympic Games. It's a picture that I've dreamed about."

It's a picture Davis's parents could have hardly dared dream about when they took their son down to the local track and encouraged him to chase the family dog, Sammy, to hasten his recuperation after his long illness. For his mother, to see him run in the red, white and blue of Great Britain will be the realisation of a personal dream. Ava Gordon is a Los Angelean Londoner, born in Lambeth and brought up in Shepherd's Bush.

"She went to the States to go to college," Davis says. "I don't think she saw herself staying that long, but it's now pushing 30 years. She's definitely played a big part in me running here. Without her, I'd still be in the States."

When he left the States on 7 July, Davis only expected to be in Britain for four days, to compete in the trials and then return home. He has stayed on, living and training at UK Athletics' High Performance Centre at Loughborough University, while his selection fate has been resolved - and while sections of the media have whipped up a bigger storm than they ever did when Budge Pountney was picked for the Scottish rugby union team - and subsequently captained it - on the strength that a grandparent born in the Channel Islands qualified him to represent any of the home nations.

The truth was there was no other contender for the third 400m place in the British team for Athens. Davis was the only athlete who had achieved a qualifying time. And if he can regain the form that took him to his 45.52sec clocking in Tucson in May, he could put the British 4 x 400m relay team into contention for a medal in Athens.

His first chance to do so comes this afternoon, when he runs for Britain against the United States. "It'll be interesting," Davis says, with a broad grin. "But when it comes down to it, when you get to the line, everybody's competing against everybody else. It doesn't matter what background you come from."